Device and method for straightening pressing of a flat metal product

ABSTRACT

The invention relates to a device and a method for straightening pressing a flat metal product, as well as a roll stand (300) comprising said device (100). Known straightening presses typically comprise an upper press frame having a pressing die and a lower press frame having a table for supporting the flat product to be straightened, wherein the upper press frame is arranged opposite the lower press frame and both press frames can be moved vertically with respect to one another. The problem addressed by the invention is that of providing a device (100) for straightening pressing a flat metal product, a roll stand (300) comprising said device (100) and a method for operating a roll stand (300) of this type, which enable economically efficient straightening of flat products. This problem is solved in relation to the device (100) through the subject matter of claim 1. The subject matter is characterized in that the upper press frame (110) comprises carrier elements (114) in the region of both narrow sides thereof as gripping points for a balance device for the upper work roll in a roll stand; and in that the lower press frame (120) comprises support elements (124) in the region of both narrow sides thereof for support on the stands of the roll stand.

FIELD OF THE INVENTION

The invention relates to a device for straightening pressing a flat metal product, to a roll stand, in particular a horizontal roll stand with such a device, and a method of operating such a roll stand.

PRIOR ART

Roll stands, in particular horizontal roll stands for preferably horizontal rolling of flat metal products are known in the state-of-the art since long ago. Usually, e.g., four-high rolling stands with two work and two back-up rolls are used. Traditionally the roll stands are used only for rolling steel or non-ferrous metal along a flat trajectory.

Independent therefrom, devices for straightening, i.e., flat straightening are known. Straightening typically is carried out by rolling straightening or by presses. An example of a portal straightening press is disclosed, e.g., on an internet website of a firm Fa. Dunkens, Kirchheim unter Teck, Germany. Known devices for straightening usually have an upper frame with a pressing die and a lower press frame with a table for supporting a to-be-straighten flat product, with the upper press frame being arranged above the lower press frame and with both press frames displaceable vertically relative to each other.

The drawback of the known state-of-the art consists in that rolling and straightening require two separate stand-alone machines and, thereby, more floor space and higher costs.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a device for straightening pressing a flat metal product, a roll stand with such a device, and a method of operating such a roll stand, and which would enable an economical and efficient straightening of the flat product.

This object, with regard to the device, is achieved by subject matter of claim 1. It is characterized in that the upper press frame has, in the region of both narrow sides, carrier elements which serve as contact points for a balancing device for the narrow roll in the roll stand, and in that the lower press frame has, in the region of the narrow sides, support elements for supporting the device on the roll stand supports.

The term “flat metal product” means, within the scope of the description, e.g., metal plate or sheet, or metal strip.

The term “balancing device” means not only a stand-alone balance cylinder for the work rolls but also a bending device, in particular, a bending cylinder that performs a balancing function for the work rolls.

The term “table” means basically a plate. The trough in the table or in the plate means, in the simplest case, a recess.

The table with a trough is typically provided on the lower press frame, and the pressing die is provided on the upper press frame, however, a reverse arrangement is also possible.

The inventive device which is also called a straightening cassette is formed as a slide-in module which is pushed into the roll stand instead of work rolls. The roll stand is not only operated in an operational mode “rolling” (with inserted work rolls) but also, alternatively, in an operational mode “straightening pressing” (with an inserted slide-in module instead of the work rolls). In the operational mode “straightening pressing,” the hydraulic work cylinder for the back-up rolls is used for providing a greater straightening force which can fundamentally improve straightening, in particular, of thicker sheets.

This alternative operation is particular advantageous for roll stands which because of a smaller year-long planning for production quantity (e.g., for special material), are not used at their full production capacity when operating in the rolling operational mode. Therefore, for economical reasons, they land themselves to the alternative straightening operational mode, which prevents roll stand downtime and provides for economically better use of the roll stand. The inventive device, i.e., the slide-in module for a roll stand is cheaper and occupies less space than a stand-alone (portal) straightening press.

According to a first embodiment, the upper press-frame is supported by support bolts on the lower press frame during assembly and disassembly of the straightening cassette. During a straightening operation, the support bolts are immersed in corresponding bores in the opposite press frame. In this way, an undesirable sidewise displacement of the pressing die during straightening is prevented. The vertical positioning of the upper and lower press frames relative to each other is carried out by the same cylinder that is used for deflection or balancing of work rolls during a rolling operation.

On the narrow side of the straightening cassette, preferably on the narrow side of the lower press frame, a coupling element can be provided for releasably connecting the straightening cassette to a roll exchange device. With the roll exchange device, in particular, a pull-push device, the straightening cassette can quite easily be advanced into or withdrawn from the roll stand, typically on its operational side.

According to the invention, rails which extend in a longitudinal direction of the upper and/or lower press-frame, are provided on the press frames for displacing the pressing die and/or the table which each is formed as a carriage, on the press frames in the longitudinal direction of the press frames. This configuration enables, in an advantages manner, an easy and precise placement of the pressing die above a defect to be corrected or non-flatness of a flat product to be straightened.

The upper press frame is provided, on its narrow side, with an upper drive, preferably, an upper spindle drive for displacing the pressing die-forming or table-forming carriage on the rails of the upper press frame. The lower press frame has, on its narrow side, a lower drive, preferably, a lower spindle drive for displacing the pressing die-forming carriage or the table-forming carriage on the rails of the lower press-frame. Advantageously, the drives are provided on the narrow sides of the press frames which, after the straightening cassette is pushed in the roll stand, adjoin its operational side, where a relatively simple attachment of energy and medium connections can be carried out.

The above-identified object can further be achieved by a roll stand according to claim 6 and by a method of operating the roll stand according to claim 10. The advantages of these solutions substantially correspond to the advantages discussed above with regard to the inventive device.

The control device is so formed that it provides for execution of both operational modes, i.e., the “rolling operation” and the “straightening operation.” The operator of the roll stand has a possibility to execute, as needed, any of both operational modes.

Advantageous embodiments of the roll stand and the method form subject matter of dependent claims.

The description is accompanied by six drawing figures, wherein:

FIG. 1 is a perspective view of the inventive device or the straightening cassette according to the present invention;

FIG. 2 is a longitudinal view of the device;

FIG. 3 a four-high roll stand with installed inventive device with displaced upper and lower back-up rolls;

FIG. 4 the roll stand of FIG. 3 in a start-up position for a straightening operation with the upper and lower back-up rolls in a support position for the press-frames;

FIG. 5 is a plan view of the roll stand with the pull-out device and a roll exchange device; and

FIG. 6 is a flow diagram that shows the steps for preparation of the straightening operation.

The invention will be described in details below by way of exemplary embodiments with reference to the above-referred figures. In the figures, the same technical elements are designated with the same reference numerals.

FIG. 1 shows a perspective view of the inventive device 100, also called a straightening cassette, for straightening pressing a metallic flat product, e.g., a sheet in a roll stand. The device 100 has an upper press frame 110 and a lower press frame 120. FIG. 1 shows the straightening cassette in a dismantled condition, i.e., in a non-mounted condition in the roll stand. In this condition, the upper press frame 100 is offset in a longitudinal direction with respect to the lower press frame 120. The upper press frame 110 is typically supported on the lower press frame 120 by support bolts 130. The support bolts 130 are arranged in the area of narrow sides of the press frames 110, 120 and, preferably, are fixedly secured on the upper press frame 110.

The upper press frame 110 has, in the region of its narrow sides, carrier elements 114 which during the installation in the roll stand, serve as contact points for a balancing device, e.g., a balancing cylinder for the upper work rolls in the roll stand. Similarly, the lower press frame 120 has, in the region of its narrow sides, carrier elements 124 which serve upon installation in the roll stand for support on the roll stand stanchions. More precisely, the support elements 124 are formed as slide elements or rollers which during installation of the straightening cassette in the roll stand or dismantling of the straightening cassette from the roll stand, slide or roll over rails 370 provided in the roll stand for mounting or dismounting of the work rolls; see FIG. 3.

For installation in the roll stand, the longitudinal extent of the upper and lower press frames corresponds, at least approximately, to the width of the roll stand from the drive side to the operational side.

As further shown in FIG. 1, a coupling element 140 is provided on the end side of the device 100 for releasably connecting the device or straightening cassette to a pull-push device 400. The pull-push device 400 serves for moving the straightening cassette 100 with the upper and lower press frames into and out of the roll stand region. The pull-push device is actually a (roll) exchange device, in particular, an exchange locomotive; see FIG. 5.

FIG. 2 shows a longitudinal cross-sectional view of the inventive device 100. FIG. 2 likewise shows the straightening cassette in a dismantled condition, with the upper and lower press frames offset relative to each other, as described with reference to FIG. 1. On the upper press-frame 110, preferably on its side adjacent to the lower press frame 120, rails 150-1 which extend in the longitudinal direction of upper press frame, are provided.

A pressing die 112 that is formed as a carriage, is displaceably arranged on the rails 150-1. On the lower press frame 120, preferably on its upper side adjacent to the upper press frame 110, likewise rails 150-2 which extend in the longitudinal direction of the lower press frame, are provided. A table 122 for supporting the to-be straighten flat product and which likewise formed as a carriage, is displaceably arranged on the rails 150-2, see the horizontal arrow in FIG. 2. The table 122 has, as shown in FIG. 1, a trough 123 forming space into which the material of the flat product can be pressed into or be overstretched.

On one of its end sides, the upper press frame 110 has an upper drive device 210 for displacing the formed as a carriage, pressing die 112 on the rails 150-1 of the upper press frame. Preferably, on the similar end side, the lower press frame 120 has a lower drive device 220 for displacing the formed as a carriage, table 122. The drive devices 210, 220 are preferably formed on the same end sides of the press frames 110, 120 and which lie, during the installation of the device 100 in the roll stand, on the operational side of the roll stand. With the drive devices 210, 220 which, preferably, formed as spindle drives, the table 122 and the pressing die 112 can be suitably positioned, independently from each other by being displaced along the rails 150-1, 150-2. Suitably positioned means that the table 122 and the pressing die 112 are so displaced relative to each other that the pressing die 112 is precisely positioned in the region of the to-be-straighten non-flatness of the flat product.

FIG. 3 shows that an inventive roll stand 300, here, e.g., a four-high roll stand 300 with two back-up rolls 310, 320 and, normally, with two work rolls, not shown in FIG. 3, as being dismantled. The upper back-up roll 310 and the lower back-up roll 320 are both displaced, upward and downward, respectively. Instead of work rolls, the inventive device 100, i.e., the straightening cassette is installed in the roll stand. The drawing shows that the lower press frame 120 with its support elements 124 rests on rails 370 for changing the work rolls. The upper press frame 110 is releasably supported with its carrier elements 114 on the balancing device 130 or is supported thereby in vertical direction. The balancing device 130 usually serves, when the roll stand is operated in operational mode “rolling,” for balancing, i.e., for compensating the weight force of the upper work roll. FIG. 3 shows the roll stand 300 equipped with the straightening cassette for the inventive operational mode straightening pressing.

In this case, as discussed, the balancing device serves for carrying, i.e., for compensating the weight force of the upper press frame 110. In FIG. 3, the displaced upwardly back-up roll 310 has no contact with the upper press frame 110, and the lower back-up roll 320 likewise has no contact with the lower press frame 120, thus, FIG. 3 shows the roll stand in a ready-for-use condition.

FIG. 4 likewise shows the roll stand 300 with the installed straightening cassette 100. In distinction from FIG. 3, here, the lower back-up roll 320 is advanced against the lower press frame 120 by a vertical adjusting, device 340. In this way, the lower press frame is lifted at least slightly from the rails 370 for changing work rolls and applies straightening forces acting in the vertical direction during the straightening operation. Likewise, the upper back-up roll 310 is advanced in a predetermined stop position for the upper press frame 110 by a mechanical adjusting device 360. Otherwise, the upper press frame 110 is positioned in the stop position against the upper back-up roll 310 force-lockingly and without a clearance by the balancing device 330. The described and shown in FIG. 4 position defines a start-up condition of the roll stand for the straightening operation. A free space into which a to-be-straightened flat product can be advanced can be seen between the pressing die 112 and the table 122.

FIG. 5 has been discussed above in connection with the description of FIG. 1.

Below, the method of operating the roll stand 300 in the inventive operational mode “straightening pressing” will be described in detail. At that, it should be again emphasized that the operational mode “straightening pressing” of the roll stand as an alternative to the operational mode “rolling” is freely selectable. Because the operational mode “rolling” is known since long ago, it is not described in the description above.

For preparation for installation of the straightening cassette 100 in the roll stand, the upper and lower back-up rolls are displaced, and the work rolls are removed from the roll stand over the rails 370. The straightening cassette is located outside of the roll stand. The upper press frame 110 is typically supported by the support bolts 130 on the lower press frame 120 offset in the longitudinal direction relative thereto and projecting toward the drive side of the roll stands as shown in FIGS. 1 and 2. The installation of the straightening cassette 100 in the roll stand includes the following steps:

-   -   Advancing the straightening cassette on the rails 370 for the         work rolls exchange into the roll stand by the pull-push device         400 until it stops inside against the drive side stanchions of         the roll stand;     -   Closing the upper work roll locking means;     -   Lifting the balancing device 330 for supporting the upper press         frame 110 on its carrier elements 114;     -   Further advancing the straightening cassette with the work roll         exchange device in the roll stand until the lower press frame         120 rests with its support elements 124 on the drive side         stanchions of the roll stand; and     -   Closing the lower work roll locking means.

At that, the lower press frame 120 is displaced relative to the upper press frame 110 that was blocked by the drive side of the roll stand upon its horizontal displacement. The lower and upper press frames are not offset relative to each other anymore but also are symmetrically arranged opposite each other. Simultaneously, in the opposite position, the support bolts 130 are displaced in complementary openings in the oppositely located frame. In the opposite position against opening, the support bolts do not carry any support function for the upper press frame; the support function is taken over by the balancing device for the work rolls.

After installation of the straightening cassette in the roll stand, both the roll stand and the straightening cassette are brought into the start-up condition for “straightening operation,” as shown in FIG. 4. To this end, the following steps are executed:

-   -   Displacing the upper back-up roll downwardly 310 in an upper         stop position for the upper press frame;     -   Placing the upper press frame against the upper stop position         with a balancing cylinder 330;     -   Lifting the lower back-up roll 320 to a lower stop position for         the lower press frame and displacing the lower press frame 120         in clearance-free contact with the lower back-up roll in the         lower stop position in which the lower press frame does not have         any contact anymore with the rails 370 for work roll exchange.

In the start-up position for the operational mode “straightening pressing, between the pressing die 112 and the table 122, a free space into which the to be-straightened flat product can be advanced, still remains, as was described above with reference to FIG. 4.

The operational mode “straightening pressing” itself has, starting from the start-up condition of the roll stand the straightening pressing operation, has the following steps:

-   -   Advancing a flat product in the roll stand into the free space         between the pressing die 112 and the table 122;     -   Positioning the to-be-straightened flat product with regard to         the table of the lower press frame 120 in such a way that the         to-be-eliminated non-flatness is lifted upward to the upper         press frame 110 and is located between the two press frames;     -   Positioning the table 122 with the flat product and/or the         pressing die 112 by a traverse movement of the pressing die or         the table so that the pressing die is located above the         non-flatness; and     -   Straightening the flat product by lifting the lower back-up roll         with the lower press frame supported thereby with, preferably,         hydraulic vertical adjusting device for the back-up roll for         pressing the flat product located on the table of the lower         press frame against the pressing die 112 on the upper press         frame for deleting the non-flatness of the flat product.

The above-described straightening of the flat product by pressing the flat product from below is selected when the vertical adjusting device is located in the roll stand below and is available for pressing the lower back-roll 320 upward. Generally, the position of the pressing die and the trough can be changed in comparison with the embodiment according to FIGS. through 4, so that in this case the to-be-deleted non-flatness extends downwardly. In this case, the pressing die presses from below against the above-located table with the trough.

Before the start of the straightening pressing operation, a plan of straightening pressing of the flat product can be established taking into consideration the flat product data, such as property of the material, its thickness and width and taking into consideration the information about the non-flatness, location of the defect, size and depth and the type of the defect, and optionally by providing a process model.

The to-be-straightened non-flatness in the flat product can be, e.g., evaluated with a scanner automatically by providing a picture. The information about the non-flatness can be produced at least partially automatically by evaluating the scanned picture.

In order to insure good straightening results, respective actual position of the flat product can be regularly monitored and, in case of deviation from a respective set position, is corrected.

After execution of the straightening operation, the result of the straightening pressing process can be monitored and compared with a predetermined set result. I.e., the result can be checked as to what extent the initial non-flatness in the flat product is already eliminated. At a determined deficient quality of the straightening result, i.e., an unsatisfactory elimination of non-flatness, the straightening operation can be repeated. After the straightening operation is completed, i.e., after elimination of non-flatness, the back-up rolls 310, 320 are displaced, and the press frames are removed. For dismantling of the straightening cassette, the above-described steps for installation of the straightening cassette in the roll stand are executed in reverse order.

All of the process steps can be carried out manually or be controlled automatically. It is preferable, however, that at least some of the steps are executed automatically.

LIST OF REFERENCE NUMERALS

-   100 Device -   110 Upper press frame -   112 Pressing die -   114 Carrier elements of the upper press frame -   120 Lower press frame -   122 Table -   123 Trough -   124 Support elements of the lower press frame -   130 Support bolts -   140 Coupling element -   150-1 Rails on the upper press frame -   150-2 Rails on the lower press frame -   210 Upper drive -   220 Lower drive -   300 Rolling stand -   310 Upper back-up roll -   320 Lower back-up roll -   330 Balancing device -   340 Vertical adjusting device for the lower back-up roll -   350 Stanchions of the roll stand -   360 Vertical adjusting means for the upper back-up roll -   370 Rails for work rolls in the roll stand -   400 Pull-push device or roll exchange locomotive 

1. A device (100) for straightening pressing of a flat metal product comprising: an upper press frame (110) and a lower press frame (120), wherein the upper press frame has a pressing die (112) and the lower press has a table (122) with a trough for immersion of the pressing die, or vice versa; and wherein the upper press frame (110) and the lower press frame (120) are arranged opposite each other and are displaceable relative to each other, characterized in that the upper press frame (110) has, in a region of both narrow sides, carrier elements as contact points for a balancing device for an upper work roll of a roll stand, and the lower press frame (120) has, in a region of both narrow sides, support elements (124) for being supported on stanchions of the roll stand.
 2. A device according to claim 1, characterized in that support bolts (130) are provided in the region of both small sides of the lower or upper frame (110, 120), and openings for receiving the support bolts are provided in a respective oppositely arranged press frame for receiving the support bolts.
 3. A device according to claim 2, characterized in that a coupling element (140) is provided on a narrow side of the device (100), preferably on a narrow side of the lower press frame (120) for releasably connecting the device (100) with a pull-push device (400).
 4. A device according to claim 1, characterized in that rails (150-1, 150-2) which extends in a longitudinal direction of the upper and/or lower frame(s) (110, 120), are provided thereon, and that the pressing die (112) of one of the press frame and/or the table (122) with a trough of the other press frame are formed, respectively, as a carriage for displacement on the rails in the longitudinal direction of the press frames.
 5. A device according to claim 4, characterized in that the upper press frame (110) has, on one of the narrow sides thereof, an upper drive (220), preferably, an upper spindle drive for displacing the pressing die-forming carriage or the table along the rails (150-1) of the upper press frame, and/or the lower press frame (120) has, on one of the narrow sides thereof, a lower drive device (220), preferably, a lower spindle drive for displacing the table-forming or the die-forming carriage along the rails (150-2) of the lower press frame.
 6. (canceled)
 7. A roll stand according to claim 19, characterized in that in an initial position for a straightening operation, the lower press frame (120) is supported against the lower back-up roll, and the upper press frame (110) is supported with the support elements (114) thereof against the balancing device for the upper work roll and is adjusted by the balancing device (330) against the, located in the initial position thereof, upper back-up roll.
 8. A roll stand according to claim 19, characterized in that there is provided a control device for the roll stand for controlling operation of the roll stand in an operational mode “rolling” of a roll stock or, in an alternatively selected operational mode “straightening pressing” for straightening pressing the flat product.
 9. A roll stand according to claim 19, characterized in that the roll stand is provided with rails (370) for changing the work rolls, and the support elements (124) of the lower press frame (120) are formed as slides or rollers for sliding or rolling on the rails (370) for changing the work rolls.
 10. (canceled)
 11. A method according to claim 20, characterized in that after elimination of the non-flatness, both back-up rolls and the upper and lower press frames are displaced again in the initial position for straightening pressing.
 12. A method according to claim 20, characterized in that for preparation of the installation of the device (100) in the roll stand, a) the upper and lower back-up rolls are displaced in opposite direction away from each other, b) the work rolls are removed from the roll stand, and c) the upper press frame (110) is displaced over the back-up roll (130) in a longitudinal direction and supported on the lower press frame (120), projecting toward a drive side of the roll stand, and in that the installation of the device (100) in the roll stand comprises the following steps: advancing the device (100) with a roll exchange device over the rails (370) for changing work rolls until the upper press frame is stopped inside against the drive-side stanchions of the roll stand; closing the upper work roll locking device; lifting the balancing device (330) for the work roll for supporting the upper press frame (110) on the carrier elements thereof; further advancing the device with the push-pull device (410) in the roll stand until the lower press frame (120) is stopped inside against the drive-side tranchions, wherein the support bolts (130) are pushed into opposite complementary openings in oppositely located press frame; closing the lower work roll rolling device; and establishing an initial position for the “straightening operation.”
 13. A method according to claim 12, characterized in that the establishing initial position of the roll stand for the “straightening operation” includes the following steps: displacing the upper back-up roll (310) downwardly in an upper stop position for the upper press frame (110); clearance-free positioning of the upper back-up roll (310) in the upper stop position with the balancing device; lifting the lower back-up roll (320) in a lower stop position for the lower press frame with the lower back-up roll abutting the lower press frame (120) in the lower stop position.
 14. A method according to one of claim 20, characterized in that before execution of steps according to claim 10, a plan of straightening pressing of the flat product is created, taken into consideration data about the flat product such as type of the material, thickness, width as well as taken into consideration information regarding the non-flatness such as position of the defect, size, depth, and type of the defect and, optionally, using a process model.
 15. A method according to one of claim 14, characterized in that the non-flatness is automatically captured with scanned pictures, and the information about the non-flatness is at least partially automatically developed by evaluation of the scanned pictures.
 16. A method according to one of claim 14, characterized in that during the execution of the steps according to claim 10, an actual position of the flat product is regularly monitored and in case of deviation, is corrected in accordance with a respective set position.
 17. A method according to claim 16, characterized in that after carrying out the steps according to claim 10, results of the straightening pressing process are monitored and compared with predetermined set result, and if unsatisfactory quality is established, the steps according to claim 10 are repeated.
 18. A method according to claim 20, characterized in that the operational steps can be carried out manually or at least partially automatically.
 19. A roll stand (300), in particular, a horizontal roll stand, comprising: upper and lower back-up rolls (310, 320); work rolls (not shown); a balancing device (300) for the upper work roll; and a preferably hydraulic vertical adjustment device for the lower back-up roll, characterized in that instead of the work rolls, a device (100) for straightening pressing of a flat metal product is insertable in the roll stand, the device comprising: an upper press frame (110) and a lower press frame (120), wherein the upper press frame has a pressing die (112) and the lower press has a table (122) with a trough for immersion of the pressing die, or vice versa; and wherein the upper press frame (110) and the lower press frame (120) are arranged opposite each other and are displaceable relative to each other, characterized in that the upper press frame (110) has, in a region of both narrow sides, carrier elements as contact points for a balancing device for an upper work roll of a roll stand, and the lower press frame (120) has, in a region of both narrow sides, support elements (124) for being supported on stanchions of the roll stand.
 20. A method of operating, in an operational mode “straightening pressing,” a roll stand (300), comprising: upper and lower back-up rolls (310, 320); work rolls (not shown); a balancing device (300) for the upper work roll; and a preferably hydraulic vertical adjustment device for the lower back-up roll, wherein instead of the work rolls, a device (100) for straightening pressing of a flat metal product is insertable in the roll stand, the device comprising: an upper press frame (110) and a lower press frame (120), wherein the upper press frame has a pressing die (112) and the lower press has a table (122) with a trough for immersion of the pressing die, or vice versa; wherein the upper press frame (110) and the lower press frame (120) are arranged opposite each other and are displaceable relative to each other; and wherein the upper press frame (110) has, in a region of both narrow sides, carrier elements as contact points for a balancing device for an upper work roll of a roll stand, and the lower press frame (120) has, in a region of both narrow sides, support elements (124) for being supported on stanchions of the roll stand, the method being characterized in that proceeding from an initial position for a straightening pressing operation, comprises the following steps: advancing the flat product in the rolling stand and positioning the to-be-straightening flat product relative to the table (122) with a trough of one of the press frames so that a to-be-eliminated non-flatness extends toward another, pressing die-carrying frame and is located between both frames; positioning the table (122) and/or the pressing die (112) relative to a flat product defect in such a way by a transverse movement of the pressing die or the table that the pressing die or the table are located above the non-flatness, and straightening the flat product by lifting the lower back-up roll, together with the press frame supported thereon, with the preferably hydraulic vertical adjustment device for the lower back-up roll (320) and thereby, press the flat product supported on the lower press frame from below against the pressing die (112) or the table located on the upper frame for eliminating the non-flatness of the flat product. 